In marine exhaust systems, a flexible exhaust hose is coupled between the combustion engine of a generator set (genset) and a muffler and water separator. These flexible exhaust hoses transfer the exhaust gases and the raw water from the genset to the boat muffler and water separator that are located remote from the genset. Unlike automotive exhaust system that are made of metal, which is a good noise barrier, marine exhaust hoses have to be flexible and thus are not good barriers for noise. Lately, genset noise has been reduced through better designs, thus making the radiated noise from the exhaust hose the major source of overall noise.
One technique to reduce the noise of exhaust hoses is to insulate the exhaust hose with a barrier type material. However, this is not a practical solution since the boat builder supplies the exhaust hose and the builders are typically reluctant to invest the additional time and money to insulate the exhaust hose. What is needed is a more practical technique to reduce marine exhaust hose noise.